linux-kernel - RE: [PATCH 1/5] cxl/acpi: Set ACPI's CXL

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Date:   Fri, 21 Oct 2022 15:39:41 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Terry Bowman <terry.bowman@....com>, <alison.schofield@...el.com>,
        <vishal.l.verma@...el.com>, <dave.jiang@...el.com>,
        <ira.weiny@...el.com>, <bwidawsk@...nel.org>,
        <dan.j.williams@...el.com>
CC:     <terry.bowman@....com>, <linux-cxl@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <bhelgaas@...gle.com>,
        <rafael@...nel.org>, <lenb@...nel.org>,
        <Jonathan.Cameron@...wei.com>, <dave@...olabs.net>,
        <rrichter@....com>, <linux-acpi@...r.kernel.org>
Subject: RE: [PATCH 1/5] cxl/acpi: Set ACPI's CXL _OSC to indicate CXL1.1
 support

Terry Bowman wrote:
> ACPI includes a CXL _OSC support method to communicate the available
> CXL support to FW. The CXL support _OSC includes a field to indicate
> CXL1.1 RCH RCD support. The OS sets this bit to 1 if it supports access
> to RCD and RCH Port registers.[1] FW can potentially change it's operation
> depending on the _OSC support setting reported by the OS.
> 
> The ACPI driver does not currently set the ACPI _OSC support to indicate
> CXL1.1 RCD RCH support. Change the capability reported to include CXL1.1.
> 
> [1] CXL3.0 Table 9-26 'Interpretation of CXL _OSC Support Field'
> 
> Signed-off-by: Terry Bowman <terry.bowman@....com>
> ---
>  drivers/acpi/pci_root.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index c8385ef54c37..094a59b216ae 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c

Be sure to copy linux-acpi@...r.kernel.org on patches that touch
drivers/acpi/

> @@ -492,6 +492,7 @@ static u32 calculate_cxl_support(void)
>  	u32 support;
>  
>  	support = OSC_CXL_2_0_PORT_DEV_REG_ACCESS_SUPPORT;
> +	support |= OSC_CXL_1_1_PORT_REG_ACCESS_SUPPORT;
>  	if (pci_aer_available())
>  		support |= OSC_CXL_PROTOCOL_ERR_REPORTING_SUPPORT;
>  	if (IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE))

This looks good to me though.